Minimal residue disease (MRD)

Introduction

e developed a quantitative PCR (QPCR) technique for the detection of cytokeratin 19 (CK19) transcripts in blood and bone marrow and compared this with immunocytochemistry (ICC). The aim was to monitor these assays for micrometastases in primary breast cancer patients.

Materials and methods

Bone marrow (BM) aspirates were taken 2–4 years following chemotherapy from 39 patients who had entered a trial comparing high-dose chemotherapy (n = 17) with standard chemotherapy (n = 22). The BM was tested for the presence of CK19-positive cells using ICC and QPCR. We compared this with 20 low-risk (T1N0) patients.

Results

See Table 1. A total of 232 aspirates were analysed from the high-risk patients and 100 from the T1N0 patients. The number of patients positive was therefore approximately the same irrespective of therapy in the high-risk patients, and the levels of positivity were not significantly different (PCR, P = 0.078; and ICC, P = 0.253). The levels of positivity, however, were higher in the high-risk patients than in the low-risk patients.

Table 1 Incidence of positivity

Conclusion

We have demonstrated that: (a) patients who received high-dose and standard chemotherapy showed similar results, (b) patients with a low-risk of relapse had markedly lower values as compared with high-risk primary breast cancer patients, and (c) micrometastases persist in a substantial proportion of patients.